A device of this kind is known from Netherlands Patent Application No. 76.05.687 in which it is disclosed that the resolution of the radiation absorption distribution to be determined can be substantially doubled by asymmetrical positioning of the detector device with respect to the centre of rotation. However, it has been found that artefacts occur in an absorption image obtained by means of the device described in said Patent Application. These artefacts also occur if the centre of rotation is not situated on a measuring path at the edge of the beam, but on a measuring path inside the beam, in which case the body to be examined is only partly irradiated. These artefacts are to be attributed to the fact that the measuring signals are a part of a series of measuring signals which would be obtained if the body were completely irradiated and the radiation having passed through the body were measured. Each interrupted series of measuring signals applied by the detector device for each radiation source position, consequently, includes a sudden transition from a finite measuring signal to the value zero. These transitions actually contain information which is not present in the body and which is thus artificially produced and falsifies the image of the radiation absorption to be reconstructed.